著者

永見 初太郎

出版者

公益社団法人 応用物理学会

雑誌

応用物理 (ISSN:03698009)

巻号頁・発行日

vol.25, no.1, pp.10-15, 1956

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A study is made on the illumination of viewing screen for radiography by the theory of vision. It is concluded that.<br> 1) The min. discriminating difference of uniform objects which can be appreciated in radiograph decreases with increasing film density, film constant and illumination of the view-ing screen.<br> 2) The subjective sharpness depends on the illumination and the film density or distribu-tion of densities, is almost always better than physical sharpness, and rises with decreasing illumination of the viewing screen.<br> 3) The max. value of subjective contrast is influenced by the phenomenon of irradiation, and depends on the illumination and the film density, rises with decreasing illumination of the viewing screen.<br> 4) The subjective contrast rises, if the shortwave-length light of the viewing screen is cut off by filter up to approximately 500m&mu;.<br> 5) It is to be desired that the intensity of illumination of the viewing screen for radio-graphy be widely adjustable.